Ultra high frequency electron discharge device system



Aug. 12, 1947. I

ULTRA HIGH FREQUENCY ELECTRON DISCHARGE DEVICE SYSTEM Fild Aug. 2e, 19442 sheets-sheet 1 .H Ud

Aug. l2, 1947. R. sLoss 2,425,352

ULTRA HIGH FREQUENCY ELECTRON DISCHARGE DEVICE SYSTEM n Filed Aug. 26,1944 4 2 sheets-sheet 2- ATTORNEY Patented Aug. 12, 1947 ULTRA HIGHFREQUENCY ELECTRON DISCHARGE DEVICE SYSTEM Robert Sloss, Audubon, N. J.,assignor to Radio Corporation of America, a corporation of Dela- WareApplication August 26, 1944, Serial No. 551,289

(CL. Z50-36) 4 Claims.

The present invention has for its primary object to provide a frequencyconverter or mixer circuit suitable for use at very high frequencies ofthe order of 3000 megacycles.

Another object is to provide a compact, very high frequency convertersystem suitable for use in a radio relaying system adapted to receiveangular velocity modulated waves and to convert l these waves to wavesof another frequency.

The frequency converter of the invention includes a concentric lineresonator at whose high voltage end there is mounted a non-linear devicein the form of a crystal detector bridging the space between the innerand outer conductors of the resonator. This detector is connected at oneend to the outer conductor of the resonator and has its other endprotrude into the interior of the hollow, inner conductor through anaperture in the inner conductor. The resonator is fedwith waves of twodifferent very high frequencies so as to cause the detector to produce abeat frequency equal to the difference frequency. Both waves developvoltage on the line resonator, and hence, voltage at both very highradio frequencies is developed across the terminals of the crystalrectifier. i

A feature f the invention lies in the mounting of the local oscillatorand its associated cavity resonator, as a result of which it ispossible, by a simple adjustment, to move as an integral unit the entireoscillator assemblage including the output probe.

A description of the invention follows in conjunction with a drawing,wherein:

Fig. 1 schematically illustrates the frequency converter or mixercircuit of the invention, in-

' cluding the associated local beating oscillator;

Fig. 2 illustrates in detail the mechanical assemblage of the circuitelements of Fig. 1, particularly the local oscillator and frequencyconverter, and the manner in which thelocal oscillator unit can be movedby a simple adjustment, in accordance with the invention; and

Fig. 3 is a side View of the apparatus of Fig. 2

as seen looking in the direction of the arrow 3 with the oscillatorremoved.

Throughout the figures, the same or equivalent parts are given the samereference characters.

Although the present invention is hereinafter described with particularreference to a radio relaying system adapted to receive angular velocitymodulated waves, it should be clearly understood that it is not limitedthereto and has more general uses.

Referring to Fig. 1 in more detail, there is shown a source of inputwaves of a mean frequency of 3000 megacycles in the form of atransmission line 100. This line may extend to a suitable receivingantenna (not shown), or any other source of waves. The energy of 3000megacycles impressed upon the line may be suitably modulated as tofrquency, such that the input frequency varies plus and minus 1.17megacycles, by way'of example. Line 100 is provided with a surroundingmetallic conducting shield 102 which is grounded at 104. The frequencyconverter c-r mixer comprises a metallic cavity resonator 106 which ispreferably cylindrical in shape. This resonator has its external surfacegrounded at 104. Coupling between the cavity resonator 106 and the inputline 100 is made by means of loop 105. In the alternative, line 1D0 maybe replaced by a wave chute or guide.

Extending within the resonator 106 and connected to one of its bases iscylindrical line section 190 whose base 19| is adjacent and spaced fromthe metal circular base 192 carried by metal bellows 1I I. The linesection 190 acts as an inductance and is tuned by means of thiscylindrical metallic bellows 1II having, as indicated, springycorrugated side walls. By means of the bolt 1 I3 and nut 1 I 5, thecapacity between plates 19| and 192 is adjusted as is also the volume orinternal cubical content of the resonator. Preferably the line section190 is approximately one-quarter wave-length long-here about 3A of oneinch. This line section is tuned by adjustment of plate 192 to thefrequency of the `waves received and fed in at loop 105. A crystaldetector 198 is mounted as shown at the high voltage end of the linesection 190 with one terminal 195 in electrical contact with a wall ofresonator 106 and its other terminal 196 protruding through opening 191in the cylindrical' line section 190. Terminal 136 is connected toconductor or line 1I0. As a result, the crystal detector recties thewaves fed in at 105 and 1I8 and feeds the resulting difference frequencyof about 30 megacycles into line 1 I 0.

The cavity resonator 106 is also supplied with high frequencyoscillations by means of a capacity end plate 1|8 located in theinterior of the cavity resonator and fixed to the inner conductor of anexposed section of coaxial transmission line 122 which inner conductorextends into the resonator. The conductor 120 is excited by an automaticfrequency controlled high frequency oscillator operating in theneighborhood of either 3030 megacycles or 2070 megacycles. Theoscillator will be described more fully later.

3 The crystal detector 108 recties the waves fed in at 105 and 1I8 andproduces a lbeat frequency of 30 megacycles which is fed through line1I0 shielded by the surrounding conductor 1 I2 to the pirrnary coil 1 I5 of a transformer whose secondary coil 126 is tuned by condenser 128.The output of the tuned circuit 126, 128 is fed through line 132 to thefirst stage of suitable intermediate fre-v quency amplifiers andlimiters.

The high frequency oscillator 138 operates in the neighborhood of 2070megacyclesv or 3030 megacycles. The oscillator comprises an evacuatedcontainer 138, a cathode 134 grounded at 136, a negatively biased plate156, a cavity resonator 142 charged with voltage of a positive polarityfrom -battery 298, and a grid 144 connected to the resonator 142. Theresonator 142 (shown in cross section) is cylindrical in shape and ismade of metal. This resonator has end plates or bases 152, 154 which areperforated and to which are attached the hollow metallic inner tubularconductors 146, 150. The metallic tubes 145, 150 are separated at anintermediate point so as to provide a gap 148. Oscillations are set upin the cavity resonator 122 and wave output is derived from theinductive loop 100 coupled to the space Within the cavity'resonator 142.The

external surface of the cavity resonator 152 is` hence, its frequency ofoperation. Or, if. desired,`

a metallic bellows adjustment, such as that provided for the cavityresonator 106 may be proand the capacity plate vided for cavityresonator 142, but in this case,

of course, the container 138 should be hermetically sealed to resonator142 so that a portion of its external surface containing and otherwisesupporting the metallic bellows structure would be exposed for externaladjustment.

'I'he outputappearing in the tuned circuit 120, 128 .would be, for theexample chosen, a Wave having a mean frequency of 30 megacycles andmaximum frequency deviation of L1.1'1 megacycles. This wave is fed tosuitable intermediate frequency amplifying, limiting and discriminatordetector stages.

Figs. 2 and 3 show in greater detail a mechanical arrangement ofapparatus which the oscil` lator 138 and mixing and detecting system 106of Fig. 1 may take. Fig. 2 is a plan view of the oscillator 138 and themixing and detecting apparatus 106, the latter being shown in crosssection for a clearer understanding of the apparatus. Fig. 3 is a Viewof Ythe apparatus of Fig. 2 seen looking in the direction of arrow 3with the oscillator 138 removed. In Fig. 2, oscillator tube 138 is ofthe '126A-B type manufactured by the Western Electric Company. Adjustingbolt or screw A100 is used for the purpose of adjusting the volume ofthe cavity resonator Within the oscillator tube, and hence the frequencyof operation.

By rotating bolt A102, bracket A104 may be m'oved vertically along thegrounded metallic support A106 in order to control the position of theconductor 120 and capacity plate 1I8 within the cylindrical housing 105of the cavity resonator. Movement of the bracket A104 will move theentire oscillator tube `assemblage including oscillator tube 138 and itsassociated cavity resonator 4 1I8, as a result of which the space withincylinder 106 between line section 190 and the capacity plate will bevaried.

Crystal detector 108 has` its upper terminal connected to the lead 1I0corresponding to the internal conductor 1 I 0 of Fig. l. vThisconnection is mad/e by way of the spring contact A1I0 contacting theupper terminals of the crystal 108 and insulatingly supported upon thebase of and passing through the metal cylinder 106. The lower terminalof the crystal 103 is in direct/contact with the grounded cylinder 106.

As shown in Fig. 3, the antenna lead within the external groundedconductor 102 is held within the split clamp. A which is locked againstthe external conductor 102 by adjustment of theY nut A122. It will benoted that the internal conductor100 is looped at 105 and soldered orotherwise xed to and connected directly to the eX- ternal conductor 102.Hence bysimply moving external conductor 102 to the right orto the left,as shown in Fig. 3, the antenna coupling may be adjusted. It will benoted thatrthe antenna coupling loop 105 projects into cylinder 10B inva direction substantially at right angles tothe positionV of theconductor 120, the latter of which establishes communication with thehigh frequency oscillator 138,. i

The discriminator detector is diagrammatically illustrated at 208 inFig. 1 across the output terminalsof which are. connected resistors 102,184, which, as will be explained more fully later, pro-- vide automaticfrequency controlling voltages. These voltages may then be used tocontrol the frequency of oscillator 138 so as to maintain the beatfrequency waves within the pass band of intermediate frequencyamplifying and limiting stages.

The frequency controlling circuit fo-r the oscillator 138 from which the`automaticfrequency controlling voltages are derived, is illustratedVschematically in Fig. Vl in connection .with vacuum tube 160. Morespecifically, a source 'of voltage 165 is connectedacross the leads orterminals 116, 118, and these terminals are connected to a potentiometer114. By properly adjusting the tap 112 on potentiometer 114, and byproper choice of values for other circuit elements, the current 'flowthrough, or the conductivity of tube 160, having the anode 182, grid164, andthe cathode 168, may be controlled so that the voltage'appliedthrough leadk 158 upon the plate 156 'is of adesired value, such as vforexample, vo1ts. As indicated, the plate circuit for tube 160 is returnedto ground through a resistor 15| shunted by condenser 102erv and throughthe ground'connection 163 to the source of potential 165. It should,therefore, be clear that the automatic frequency controlling voltagesappearing across resistors 182 and 184 will vary the -current flowthrough the tube 160 and hence its effective resistance. Consequently,the voltage in lead 158 will vary in such' ed in angle frequency orphase deviation with the modulated common sub-carrier wave. Thisreproduced sub-carrier at the relaying point, employing the frequencyconverter of the invention, was then used to directly frequency modulatea new high frequency carrier having a value and frequency suitable forretransmittal. Such a relaying system was found effective in minimizingcross-modulation and distortion.

Various alteration and modifications of the present invention may becomeapparent to those skilled in the art and it is desirable that any andall such modifications and alterations be considered within the purviewof the present invention except as limited by the hereinafter apl pendedclaims.

Having now described my invention what I claim is:

1. An ultra high frequency device including a hollow electrically closedmetallic chamber adapted to have periodically repeating electromagneticwaves produced therein, a bracket mounted on the exterior of saidchamber, an electron discharge device circuit assemblage supported fromsaid bracket in spaced relation to said chamber, said assemblageincluding an electron discharge device, an energy coupling elementcarried by said assemblage and extending into the interior of saidchamber through an aperture in said chamber, and means for adjusting theposition of said assemblage and coupling element as an integral unitrelative to said chamber.

2. An ultra high frequency device including a hollow electrically closedmetallic chamber adapted to have periodically repeating electromagneticwaves produced therein, a bracket mounted on the exterior of saidchamber, an electron discharge device circuit assemblage supported fromsaid bracket in spaced relation to said chamber, said assemblageincluding an electron discharge device and hollow metallic resonatorsupported by said Ibracket, an energy coupling element carried by saidassemblage and extending into the interior of said chamber through anaperture in said chamber, and means for adjusting the position on saidbracket of said assemblage and coupling element as an integral unitrelative to said chamber.

3. An ultra high frequency device including a hollow electrically closedmetallic chamber adapted to have periodically repeating electromagneticwaves produced therein, a bracket mounted on the exterior of saidchamber, an oscillator circuit assemblage supported from said bracket inspaced relation to said chamber, said assemblage including an electrondischarge device and a frequency controlling metallic resonator, anenergy coupling element carried by said assemblage and extending intothe interior of said chamber through an aperture in said chamber, meanson said assemblage for changing the operating frequency of saidfrequency controlling resonator, and means for adjusting the position ofsaid assemblage and coupling element as an integral unit relative tosaid chamber.

4. An ultra high frequency device including a hollow electrically closedmetallic chamber adapted to have periodically repeating electromagneticwaves produced therein, a bracket mounted on the exterior of saidchamber, an oscillator circuit assemblage supported by said bracket inspaced relation to said chamber, said assemblage including an electrondischarge device and a frequency controlling metallic resonator, anenergy coupling probe carried by said assemblage and extending into theinterior of said chamber through an aperture in said chamber, means onsaid assemblage for changing the operating frequency of said frequencycontrolling resonator, and a rotatable element carried on said bracketfor adjusting the position of said assemblage and probe relative to saidchamber, to thereby vary the coupling between said oscillator circuitand said chamber.

ROBERT SLOSS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,106,713 Bowen Feb. 1, 19382,191,271 Carter Feb. 20, 1940 2,223,835 Smith Dec. 3, 1940 2,350,907Kroger June 6, 1944

